The invention relates to a device for passive friend-or-foe discrimination of targets, in particular of airborne targets, wherein the target to be identified is observed by means of a video camera.
Modern fighter aircraft or anti-aircraft batteries have target-tracking missiles which permit fighting enemy aircraft already from large distance. The distances to the aircraft to be fought at the moment of firing the target-tracking missile may be so large that the targets cannot be identified unambiguously. Therefore, the risk exists that erroneously a "friendly" aircraft is fought.
In order to avoid erroneous killing of the wrong aircraft, "IFF"-apparatus (identification friend or foe) are known. Such an IFF-apparatus transmits challenging signals, which "ask" the target aircraft, whether it is a friend. If the aircraft is a friend and has a corresponding IFF-apparatus, it understands this inquiry. It will then transmit a coded answer that it is "friendly". The IFF-apparatus may operate with radio waves, RADAR or laser.
These IFF-apparatus suffer from the disadvantage that the challenged aircraft has to have a corresponding response apparatus. Usually, the correct answers are changed daily. This presents problems with multi-national formations. A further disadvantage is that it is an active procedure: A challenging signal is transmitted. By this challenging signal, the challenger declares himself to a possible enemy.
Passive identification apparatus for friend-or-foe discrimination are known for two-seater combat aircraft, these apparatus operating with a video camera. By means of the video camera, a highly magnified image of the target is generated on a monitor for the view of the fighter observer. This permits identification ranges of about 20 km to be reached. Problems result from the fact, that the image is not stable due to vibrations of the aircraft. The fighter observer has to concentrate on the image during rather long time, in order to safely identify the target.